Enzymatic optical biosensors for healthcare applications

Abstract

Enzymes are one of the most studied biorecognition elements for biosensing applications. Enzymes are known to offer a distinctive advantage of catalytic biorecognition with simultaneous signal amplification offering excellent sensitivity and selectivity. The enzyme linked immunosorbent assay (ELISA) remains a gold standard technique for biosensing in hospital settings. The evolution of enzymatic optical biosensors has seen development of novel nanostructured substrates for loading the enzymes, customized for the type of enzyme and the specific method of optical transduction. Various novel chromogenic and fluorogenic substrates are being designed for detection of a wide range of analytes, such as, disease biomarkers, drugs and hormones. Design and development of optical enzymatic biosensors for point of use is primarily focused on developing substrates, immobilization chemistries for maximally retaining the efficiencies and stability of the enzymes, and coupling of the enzyme catalytic activity with the optical platform. This article encompasses an overview of different types of enzymatic optical biosensors, customization of substrates for enzymatic detection, immobilization methods and discussion on the optical enzymatic sensors in commercial use today. Of particular interest are the discussions in materials and methods of improving enzymatic stability and preservation of its activity using metal organic frameworks and non-covalent methods of binding, use of nanozymes, the translation of the interface chemistries on to substrates easily integrable with pocket electronic gadgets for easy use and prospects in use of enzymatic optical sensors as wearables. The potential journey of some of these technologies from laboratory to real healthcare applications are discussed.